tools/version.sh: Use backup files on Win32 Windows doesn't permit us to edit a file in-place with Perl. So create backup files when we perform the edit, and remove them when we are done. This is a tad slower on POSIX systems, but is much more portable. Change-Id: I429c7d698924cb32e709363f5da82f7232bbdab2 Signed-off-by: Shawn O. Pearce <spearce@spearce.org>